Fuel injection device



June 12,1945. 'WAEBER I 2,378,155

- FUEL INJECTION DEVICE F'iled Feb. 24, 1943 INVENTOR 01m mmae/ ATTORNEYS Patented June 12, 194

FUEL INJECTION DEVICE Erwin Waeber, Winterthur, Switzerland, assignor to Sulzer Freres, SocitAnonyme, Winterthur, Switzerland Application February 24, 1943, Serial No. 476,977 In Switzerland February "I, 1942 r 3 Claims. (Cl. 299-94012) The invention relates toa fuel injection device,

whose injection pump delivers fuel in excess of what is required. The invention consists in that the fuel delivered by the pump in excess passes from the delivery space of thepump through any air bubbles that may be present. In this way troubles occurring to the injection in consequence of coking of the fuel or from the presence of air are prevented.

the nozzle space to a member controlling the Preferably the injection pump plunger is provided with a peripheral recess which is defined in part by an oblique edge, which controls the return flow of the fuel delivered in excess through the nozzle space. It is recommended to construct the return flow member in such a way that the excess of fuel passes through the nozzle space before the injection period.

The single figure of the drawing shows one embodiment of the invention.

The pump plunger 1 is driven through a roller guide 2 by-the cam 3 of the camshaft 4. The cylinder 5 of the fuel pump is connected to the fuel tank 6 through a delivery pipe 1 and a return pipe 8. Part of the fuel delivered by the pump reaches the nozzle chamber l0 through the passage 9 and is then injected through the nozzle I l into the combustion space l2.

During the sucton stroke of the plunger I, the fuel is forced by the feed pump l3 through the pipe I past the valve ll into the delivery chamber lb of the pump. During the delivery stroke of the plunger I fuel flows through the delivery valve 18 and the passage 9 into the nozzle chamber l0.

As long as the return passage I! is in connection with the pipe 8 through the space formed by the recess l8 in the plunger I, the fuel delivered'inexcess flows again into the tank 6.

If the control edge 20 of the piston l breaks ofi the connection between the passage I1 and the pipe 8, the fuel delivered to the injection space I is subjected to pressure. In that way the fuel needle 2| is raised against theforce of the spring 22. The fuel can'then be injected through the I nozzle ll into the combustion space l2. After In order to prevent pressure waves forming in the delivery pipe after the beginning .of an injection stroke, and to lead away the fuel supplied in excess by the delivery pump it, a bypass having an overflow valve 24 loaded with the spring 23 is provided. The superfluous fuel then passes from the pipe 1, through the byby oil pressure in said chamber greater than the loading pressure thereon, an oil delivery chamber. a delivery conduit for conducting oil to the delivery chamber, a-passage for oil from the delivery chamber to the nozzle chamber, means for preventing return flow-of oil through said passage, a pump cylinder, a pump plunger reciprocable in said cylinder, said plunger having a forward end portion filling said cylinder, the delivery end of said cylinder communicating with said delivery chamber, the pump plunger having a peripheral recess rearwardly of said forward outer end portion providing a space between the plunger and the cylinder, an oil passage-from-the nozzle chamber, through the cylinder, to said space, and an oil, passage from said space, the

plunger having a control edge defining a portion of said space and shaped to cut off flow of oil from said space to the oil passage leading therefrom at a predetermined position of the plunger during the advance thereof, to control the point during the advance of the plunger at which further forward movement thereof begins applying pressure on the oil in the nozzle chamber to cause injection.

2. An oil injection device as set forth in claim 1 having means to vary the -position 'at which the device as set forth in claim 

